Control system development for supply air pressure in air handling unit

Abstract

Air handling unit (AHU) is one of the critical component in air conditioning and mechanical ventilation (ACMV) system. Huge belt-driven fan was used in AHU to facilitate air circulation and the fan itself used up most of the energy in AHU. Static air pressure generated by the fan can determine the efficiency of the AHU. Hence, there is a need to develop a good control system by controlling the fan based on static air pressure. Experiments were conducted at three different ranges using LabVIEW simulation and the empirical models of the fan were then derived. The empirical models were then used to design the Proportional-integral-derivative (PID) controllers based on the three different tuning strategies, Ziegler-Nichols (Z-N) method, gain and phase margin (GPM) method and internal model control (IMC) method. It was concluded that GPM PI controllers and IMC PID controllers provide the best performance in terms of good stability, short settling time and minimal overshoots when implemented to control the fan.